Technical Field
The present invention relates to a system and a method for building a 3D model of an area of interest on the surface of a planet.
Description of Related Art
When building a three-dimensional (3D) model of a part of the Earth's surface one can use a camera system suitable for providing pictures from which stereo pairs can be generated. Then that camera system can be mounted on an airplane (sometimes together with a LIDAR-system for providing some height information, however, other height-measurement systems are possible as well). One can fly with the airplane over the area of interest, take pictures of the area of interest together with some height information and then process the pictures together with the height information to achieve a 3D model. This is well known in the state of the art.
Sometimes, however, it is not possible to use airplanes for providing pictures. This might be the case when there is no allowance for doing so, for example, due to flight-restricted areas. Another example is that the area of interest is too remote to be economically covered by airplanes or that the area of interest is too big to economically fly over it with airplanes. This might especially be the case when a 3D model of the whole Earth's surface or at least of the parts of the Earth surface which are covered by land should be provided.
3D models have been built via images taken by satellites as well. However, satellites are expensive to construct, to put into orbit and to control. Existing satellites aimed at providing images of the Earth's surface are mainly used for providing 2D images. Only few image data from satellites are nowadays provided as stereo photos and are thus used for building 3D models. One reason is that a satellite would have to take (at least) two photos of an area from different angles. It is often of higher priority that the satellite can take a picture of another area instead of the second photo from the same area, thus achieving a higher coverage of the Earth's surface.